The present invention generally relates to an electrophotographic copying machine having a manual paper feed capability and, more particularly, to a manual paper feed inhibiting device in the electrophotographic copying device.
An electrophotographic copying machine having normal or automatic paper feed and manual paper feed capabilities and operable selectively in one of normal and manual feed modes is currently commercially available. In such copying machine, when the machine is in the normal feed mode, a copying paper in the form of either a single sheet of paper or a web of paper from a roll is automatically supplied from at least one paper supply unit towards a processing station. On the contrary, when the machine is in the manual feed mode, a copying paper usually in the form of a single sheet of paper is manually supplied through a feed mouth towards the processing station.
It has often occurred, or the necessity has often occurred that, when the machine is operating in the manual feed mode, the user of the machine manually supplies a copying paper which may be either identical in quality and size to or different from that standardized for the machines of the same brand or the same make.
In any event, the operation of the machine on the copying paper whether fed automatically during the normal feed mode or manually during the manual feed mode remain the same.
In the known copying machine of the type referred to above and disclosed, for example, in the U.S. Pat. No. 4,113,374, patented on Sept. 12, 1978, the invention of which has been assigned to the same assignee of the present invention, an arrangement has been made to interrupt the continued supply of the copying paper toward the processing station by means to interrupt the rotation of the feed rollers and/or to light a warning lamp to provide a visual indication to inhibit the manual paper feed when and so long as the next succeeding copying operation can not readily be initiated. The provision of the manual paper feed inhibiting device of this kind is effective to avoid any possible erroneous use of the copying machine and to assure a smooth and satisfactory copying operation being performed in the machine.
However, it has been found that fixing of a toner or powder image transferred onto a copying paper of relatively large thickness, such as Bristol board, tends to result in defects. This is because the heat fuser used in a fixing device in the copying machine is heated only to the predetermined temperature necessary to fuse toner particles on the one hand and because the thick copying paper has a larger heat capacity than that of the copying paper of relatively small thickness. In other words, although the fixing device used in the known electrophotographic copying machine is effective to fuse and then fix the powder image transferred onto the copying paper standardized for the machine the only predetermined temperature to which the heat fixing device has been heated is insufficient to fuse the powder image transferred onto copying paper of relatively large heat capacity greater than the standardized paper.